J/A+A/299/89 COYOTES II (Bouvier+, 1995)
COYOTES II: Spot properties and the origin of photometric period variations in
T Tauri stars
BOUVIER J., COVINO E., KOVO O., MARTIN E.L., MATTHEWS J.M.,
TERRANEGRA L., BECK S.C.
<Astron. Astrophys. 299, 89 (1995)>
=1995A&A...299...89B 1995A&A...299...89B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence; Photometry, UBVRI
Keywords: stars: pre-main sequence - stars: rotation - stars: activity -
accretion, accretion disks
Description (Abstract):
We present the results of a new multi-site campaign (COYOTES II) to
monitor the light variations of T Tauri stars (TTS) of the
Taurus-Auriga dark cloud. The UBVRI light curves of 19 TTS were
obtained over a two months period to search for rotational modulation
by spots. We report new period detections for IQ Tau (6.25d), LkCa-3
(7.2d), and LkCa-14 (3.35d) and confirm previously detected periods
for DF Tau (9.8d), DR Tau (9.0d), GM Aur (11.9d), and TAP 26 (2.58d).
We also report tentative periods for CW Tau (8.2d), CY Tau (7.9d), HP
Tau (5.9d), and XZ Tau (2.6d). No periods were found in the present
data set for CI Tau, DG Tau, DQ Tau, GH Tau, RY Tau, Hubble 4, TAP 45,
and TAP 57NW. Altogether, the results of this new campaign confirm the
main conclusion of COYOTES I that classical T Tauri stars
(CTTS) on average have longer rotational periods than weak-line TTS
(WTTS). The present study also confirms that rotational modulation in
WTTS is due to spots cooler than the photosphere and we show that the
amplitude of the modulation primarily reflects the amount of areal
coverage by spots. The amplitude of the light variations, and hence
the spot size, is found to increase with both rotation rate and
advancing spectral type, as expected if WTTS cool spots correspond to
photospheric regions of strong dynamo-generated magnetic fields.
Finally, combined with previous studies, these new results provide
further evidence for temporal variations of the photometric periods of
CTTS. Such variations seem to occur preferentially in CTTS whose
rotational modulation is dominated by hot spots and we therefore argue
that the observed period changes are linked to the magnetospheric
accretion process rather than to surface differential rotation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 54 374 UBVRI photometry
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name
11- 17 A7 --- HBC HBC number (Herbig Bell Catalog)
19- 28 F10.2 d JD Julian date
30- 34 F5.2 mag Vmag V magnitude
36- 39 F4.2 mag B-V []? B-V colour
41- 44 F4.2 mag U-B []? U-B colour
46- 49 F4.2 mag V-R []? V-R colour
51- 54 F4.2 mag V-I []? V-I colour
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See also:
V/73A : (HBC Catalogue, Lick Obs. Bull. 1111)
History:
* 10-Feb-2017: Julian dates (240....) corrected into (244....)
(End) Patricia Bauer [CDS] 16-Jan-1995